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Old 07-11-2008, 05:01 PM   #31
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Originally Posted by turbotrana View Post
Running a HAI may not be the best way to improve economy IMO. All I see it doing is making the IAT sensor read higher so that the fuel maps are leaned off via the temp compesation tables in the engine management system.
...why would there be these temp compensation tables that lean off the fuel maps? probably because the manufacturers think hot air is less dense air.
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Old 07-11-2008, 08:16 PM   #32
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Originally Posted by suspendedhatch View Post
Hot intake air causes the combustion chamber to run hot.
It causes the compression before the spark to be hotter which will increase octane requirements. After the spark running hot has little to do with the IAT unless the IAT has some secondary benefit.
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Old 07-12-2008, 08:59 AM   #33
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You have air temp compensation maps in most EMS. When air is cold it is more dense and needs more fuel and visa versa, when its hotter it needs less fuel. You program air temp comp so the car runs more uniformly between hot and cold climates. Its not easy to get it to run consistenly bewteen the extremes but the manufacturers do it quite well.
But if you are introducing 100deg air into the air intake you would be leaning the maps to the maximum.

There are even fuel temp comp maps



Quote:
Originally Posted by 2000mc View Post
...why would there be these temp compensation tables that lean off the fuel maps? probably because the manufacturers think hot air is less dense air.
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Old 07-12-2008, 09:11 AM   #34
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...why would there be these temp compensation tables that lean off the fuel maps? probably because the manufacturers think hot air is less dense air.
I don't think they are on cars anymore, but my 1981 Buick has a barometric pressure sensor. I guess its to modify the mixture for high altitudes. Doesn't seem to do a good job though, because when I drive it in the mountains it runs like crap, and the check engine light usually comes on.

-Jay
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Old 07-18-2008, 01:29 PM   #35
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I have not yet modified my 96 Saturn SC1, but I took two road trips this year to Arizona and in March I averaged 45 MPG and in June (with temps in the 100's) I averaged 49 MPG so I am pretty sure that HAI is the way to go. I am saving up my pennies (if I get impatient I may sell plasma too) for a Scangauge, because there will never be an answer to the general question of what's the best intake temperature. The best temperature is the one that works best for you and your car. This can only be determined through experimentation and you will need good instrumentation to nail it. I think the hardest part will be building a device to keep the temperature constant.
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Old 07-19-2008, 06:22 PM   #36
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Good luck to you 96sc1... I'm jealous of your SOHC engine!!

Been looking for a LONG time for an '01-'02 SC1 5sp in good shape w/ less than 100k for a reasonable price w/ no luck...
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Old 07-21-2008, 10:08 PM   #37
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If you let it go over 200f you will see mpg drop as ignition retards probably due to ping. I like 175f to 180f. That seems to give best results on my SC1.

Funny how people argue with things that actually work, huh? Actual results are what counts, IMO.
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Old 07-21-2008, 10:11 PM   #38
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Originally Posted by 96sc1 View Post
I have not yet modified my 96 Saturn SC1, but I took two road trips this year to Arizona and in March I averaged 45 MPG and in June (with temps in the 100's) I averaged 49 MPG so I am pretty sure that HAI is the way to go. I am saving up my pennies (if I get impatient I may sell plasma too) for a Scangauge, because there will never be an answer to the general question of what's the best intake temperature. The best temperature is the one that works best for you and your car. This can only be determined through experimentation and you will need good instrumentation to nail it. I think the hardest part will be building a device to keep the temperature constant.
When you build it, start with the intake input 1" from the header. I heard a remote sensing oven thermometer with the probe in the airbox works, if you don't want to splurge for the scangage. Since your car has the same motor as mine, I'd guess my 175f to 180f in the airbox should also work for yours.
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Old 07-21-2008, 10:15 PM   #39
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Originally Posted by turbotrana View Post
You have air temp compensation maps in most EMS. When air is cold it is more dense and needs more fuel and visa versa, when its hotter it needs less fuel. You program air temp comp so the car runs more uniformly between hot and cold climates. Its not easy to get it to run consistenly bewteen the extremes but the manufacturers do it quite well.
But if you are introducing 100deg air into the air intake you would be leaning the maps to the maximum.

There are even fuel temp comp maps
Sorry, I don't think it "leans" it if the air is heated because the system will sense less oxygen and inject less fuel to match it. The maps are designed to handle up to 247f, but from my experience, hotter than 200f seems to cause ignition retard and abnormal loss of power.
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Old 07-21-2008, 10:18 PM   #40
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Well, to be honest, that was my first ALL HIGHWAY mileage recorded in about a year and a half. I rarely take my car on trips as my g/f loves her Grand Prix w/ all it's add-on's and comforts.

I was expecting 35-36 mpg... like I said somewhere else (Gas saver's w/ record tanks thread) I recalculated the mileage like 5 times and nearly fainted when I was looking at 43 mpg... added the HAI heat shield Sunday morning and SG reported 47.2mpg on the trip home, but I'm going to add some city to it before filling up.

Thanks for the kind words!

I got grill block material from my Dad when I was home over the weekend, it's about 1/8" thick rubber matting. I figured it would hold up to the elements nicely, but I'm not sure it will stretch and hold it's shape and not deform under the pressures of 60mph.

Might be taking the car on a 640mile trip (one way... roughly 1,300 miles total) next week to SC. So my average is going to be way up if I keep reporting 40+.

I must say, I didn't think it was possible... now I'm thinking ANYTHING is possible.
If she doesn't have the supercharged Grand Prix, I bet a hot air intake would work on it, too, LOL.
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